Bacteria discovery aids food production, water purification

The search for a type of bacteria that creates better ice cream and artificial snow has suddenly become a lot easier, thanks to a discovery by Queen's University biologist Virginia Walker.

The finding has implications for improved water purification methods as well.

Until now, scientists had to go to extreme environments, such as Antarctic lakes and glaciers, to find bacteria with properties that allow them to survive at very cold temperatures. Dr. Walker and her colleagues have developed a technique that isolates such bacteria from soil in more temperate environments.

The study is highlighted in the October issue of the journal Environmental Microbiology. Also on the research team are Queen's graduate student Sandra Wilson and undergraduate student Deborah Kelly.

The new technique involves the formation of an "ice finger" to select for bacteria that will gather on the surface of the ice. Incorporating bacteria into slowly grown ice is based on a method used to purify antifreeze proteins, called ice affinity selection.

The bacteria can modify ice and water in a number of ways, explains Dr. Walker. One of the species identified demonstrates ice recrystallisation inhibition, a property useful in the production of ice cream as it prevents it from re-crystallizing and becoming crunchy.

Other species isolated in this study promote the formation of ice crystals at temperatures close to melting, which is useful in the production of artificial snow. One species is also thought to be tolerant to cold and could therefore have advantages for making snow in artificial environments such as ski centres, and in waste-water purification.

"Selecting for rare microbes that seem to stick to ice has been fun, but now the real work begins to find out what genes are responsible for this attraction," notes Dr Walker, who is internationally known for her work with insect resistance to environmental and chemical stressors.

"Our findings will help to decrease the costs involved in further discovery of such bacteria, since scientists will no longer need expeditions to the poles in order to isolate the bugs," she says. "Now they can find them in their own back yards."

The study was funded by a Queen's Research Chair and the Natural Sciences and Engineering Research Council of Canada (NSERC).